Neutron beam transport by using a magnetic lens and multi-capilary fibers

点击翻译按钮获取中文摘要

Narrow neutron beam with high intensity will open wide variety of neutron utilization fields. We studied two methods to focusing the neutoron beam. One is neutron mzgnetic lens by using 6 pole magnetic field, and the other is multi-capilary fiber.About magnetic lens, first we measured the neutron intensity through the lens and found that there exist factor 2 difference in focusing intensity between simulation and experiment. We tried to explain the reason of We found that there existed some distortion in the lens system due to strong force of high magnetic field and that this would cause gaps between magnet components. These gaps reduced the intensity. Succeedingly, we studied a function of the mfagnetic lens to forcus and pararell the neutron beasm, in which system two lenses are arranged in a series. For such a system we need neutron spin flipper to change orientation of the neutron spin between the two lenses. We observed the evidence of the neutron focusing and defocusing by using the spin flipper. This suggest the system works as neutron focusing and pararelling device.Second, we studied the wavelength dependence of neutron transmission through a multi-capirally fiber in order to know the effectiveness for utilization of white beam. A three dimensional simulation code was developed to analyze the transport characteristics. Transmission intensity depend on the radius of the capirally and also on the curvature of the fiber setting. The transmission of longer wavelength neutrons increases with the radius. Simulation indicated that the wavelength dependence of transmission could not be explained by ideal condition of the fiber and we needed to introduce distorsion in the fiber, such as waving. These data are very useful to make devices using multi-capiraly fiber.